Systems and methods for high velocity nasal insufflation

ABSTRACT

Systems, methods, and devices for humidifying a breathing gas are presented. The system includes a base unit, a vapor transfer unit, a nasal cannula, and a liquid container. The base unit includes a blower. The vapor transfer unit is external to the base unit and includes a gas passage, a liquid passage, a gas outlet, and a membrane separating the gas passage and the liquid passage. The membrane permits transfer of vapor into the gas passage from liquid in the liquid passage. The nasal cannula is coupled to the gas outlet. The liquid container is configured to reversibly mate with the base unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional application No.62/408,560, filed Oct. 14, 2016, the content of which is herebyincorporated herein by reference in its entirety.

BACKGROUND

Patients with respiratory ailments are often treated with respiratoryassist devices that deliver supplemental breathing gas to the patient.Such devices may deliver gas to the patient using high flow therapy(HFT). HFT devices deliver breathing gas at a high flow rate via aninterface such as a nasal cannula to increase the patient's fraction ofinspired oxygen (FiO2), decrease the patient's work of breathing, or doboth. That helps the patient recover from respiratory ailments, such asrespiratory distress or bronchospasms. Some HFT devices heat andhumidify the delivered breathing gas for medical reasons (e.g., tomaintain the pliability of the tissues of surfactant-deficient patients,or to preserve mucosal integrity) or to reduce patient discomfort.

Some high flow therapy systems use membrane humidification to humidifythe breathing gasses. The use of a membrane humidifier increases thepressure requirements of the system because membrane humidifiers resistthe flow of air more than non-membrane humidifiers. Furthermore,conventional high flow therapy systems use nasal cannulas with smallbore nasal prongs to increase the velocity of the breathing gassesentering a patient's airway. However, such cannulas further increase therequired pressure compared to a system using large bore nasal prongs ora face mask. These increased pressure requirements of conventional highflow therapy systems necessitate the use of wall air or a largecompressor which limits the potential field of use of high flow therapy.

Some respiratory therapy devices use a blower and a non-membranehumidifier to create humidified high flow therapy. Such non-membranehumidifiers are essentially heated water vessels through which gassesare channeled. These blower-based systems use larger bore cannulas tofurther reduce pressure requirements. However, large bore cannulas donot flush CO₂ as effectively from a patient's airway as do small borecannulas. Furthermore, non-membrane humidifiers may produce lowerquality vapor.

SUMMARY

Systems, devices, and methods for humidifying a breathing gas arepresented. The system includes a base unit, a vapor transfer unit, anasal cannula, and a liquid container. The base unit includes a blower.The vapor transfer unit is external to the base unit and includes a gaspassage, a liquid passage, a gas outlet, and a membrane separating thegas passage and the liquid passage. The membrane permits transfer ofvapor into the gas passage from liquid in the liquid passage. The nasalcannula is coupled to the gas outlet of the vapor transfer unit. Theliquid container is configured to reversibly mate with the base unit.

The systems, devices, and methods presented herein have a low pressuresystem architecture which permits the system to be operated by a lowpressure source (e.g., <275 kPa, <200 kPa, <150 kPa, <100 kPa, <50 kPa,<30 kPa, <20 kPa, <10 kPa, or any other suitable gauge pressure). Insome implementations, the system is operated by a blower, such as acentrifugal blower. By using a blower or a similar low pressure source,the base unit does not require an external source of high pressure gas.Instead, the base unit can accept gas at ambient pressure and thenpressurize the gas (e.g., internally). This allows the base unit tofunction in environments in which pressurized gas sources are notavailable (e.g., at home, in an ambulance, and/or an outpatient carecenter). In some implementations, the low pressure gas source can acceptoxygen at a low pressure or at ambient pressure. This can enable the useof an oxygen concentrator rather than an oxygen tank.

The low pressure operation of the system is enabled at least in part bythe low flow resistance of the vapor transfer unit. For example, at aflow rate of 40 LPM, the flow resistance of the vapor transfer unit maybe <70 kPa, <60 kPa, <50 kPa, <40 kPa, <30 kPa, <25 kPa, <20 kPa, <15kPa, <10 kPa, <5 kPa, <4 kPa, <3 kPa, <2 kPa, <1 kPa, or any othersuitable flow resistance. Furthermore, in some implementations, thenasal cannula has a relatively short length and has separate flow pathsfor each nasal prong to lower the flow resistance of the system. Incertain implementations, to further reduce the flow resistance, thesystem uses a large bore delivery tube to carry the output breathing gasfrom the low pressure source to the vapor transfer unit. In someimplementations, the inner diameter of the delivery tube is more thanabout 5 mm. In certain implementations, the inner diameter of thedelivery tube is about 15 mm.

In certain implementations, the liquid container has a lower surfaceformed of a flexible film. In some implementations, the liquid containercouples to the base unit using a breech lock. A combination of breechlock and a lower surface formed of a flexible film may make inadvertentdisconnection of the liquid container more difficult during operation.This is because when liquid is in the liquid container, the liquidexerts pressure against the film, which in turn exerts pressure againstthe breech lock, causing friction. Friction makes the breech lock moreresistant to torque and thus more difficult to inadvertently disconnectduring operation.

In some implementations, the liquid is heated and circulated within theliquid container without contacting the base unit. This can permit thebase unit to be reused with lower risk of contamination compared toliquid-contacting base units.

In certain implementations the blower delivers breathing gas to the gaspassage of the vapor transfer unit via a delivery tube and the liquidcontainer delivers liquid to the liquid passage of the vapor transferunit via a liquid delivery line disposed within the delivery tube. (Theliquid container may also receive a return flow of liquid from the vaportransfer unit.) Since the delivery tube surrounds the liquid deliveryline, the delivery tube insulates the liquid delivery line from ambientair. The liquid delivery line may carry heated liquid, so insulating theline can reduce the energy required to maintain the temperature of theline and thus reduce the energy requirements of the system. Moreover,some of the heat that is “lost” from the liquid delivery line in thedelivery tube enters the flow of breathing gas. This warms the breathinggas, which later facilitates the transfer of vapor into the breathinggas at the vapor transfer unit. Thus, some of the heat “lost” from theliquid lines is still conserved within the breathing circuit.Additionally, in some implementations, the blower delivers heated gasthrough the delivery tube. In such implementations, the heated gas heatsthe liquid in the liquid delivery line, thus reducing the power demandon a liquid heater.

Furthermore, by permitting the delivery tube to surround the liquiddelivery line, the system reduces the number of separate tubes that mustbe managed by the user. In conventional respiratory therapy systems inwhich a liquid container is separate from a breathing gas source, theuser may have to manage two sets of tubes: tubes from the liquidcontainer to the humidifier as well as tubes from the breathing gassource to the humidifier. In a system according to certainimplementations disclosed herein, the gas path and the liquid path areintegrated within a single tube. This reduces the amount of spaceoccupied by tubing and reduces the risk of snagging the tubinginadvertently.

Additionally, disposing the liquid delivery line within the deliverytube reduces the risk of kinking the liquid delivery line. This isbecause the bend radius of the delivery tube limits the minimum bendradius of the liquid delivery line. For example, in someimplementations, the delivery tube is corrugated, and corrugated tubinggenerally bends with a consistent radius on the inside of the bend.

According to one aspect, the system includes a base unit, a vaportransfer unit, a nasal cannula, and a liquid container. The base unitincludes a blower. The vapor transfer unit is external to the base unitand includes a gas passage, a liquid passage, a gas outlet, and amembrane separating the gas passage and the liquid passage. The membranepermits transfer of vapor into the gas passage from liquid in the liquidpassage. The nasal cannula is coupled to the gas outlet. The liquidcontainer is configured to reversibly mate with the base unit.

In some implementations, the liquid container interlocks with a surfaceof the base unit. In certain implementations, the container has asurface formed of a flexible film. In some implementations, the baseunit further includes a heating element for heating liquid, the heatingelement having a heating surface. In certain implementations, theflexible film is configured to mate with the heating surface when theliquid container mates with the base unit.

In some implementations, the blower is configured to pressurizebreathing gas to less than about 276 kPa (40 psi). In certainimplementations, the liquid container includes an impeller. In someimplementations, the base unit includes a motor. In certainimplementations, the motor is magnetically coupled to impeller. In someimplementations, the liquid passage is coupled to the liquid containerby a first tube. In certain implementations, the gas passage is coupledto the blower by a second tube. In some implementations, the first tubepasses within the second tube.

In certain implementations, the base unit includes a pressure sensorconfigured to measure pressure of the liquid in the liquid containerwhen the liquid container is coupled to the base unit. In someimplementations, the pressure sensor is configured to measure pressureagainst the flexible film. In certain implementations, the second tubehas an inner diameter of more than about 5 mm. In some implementations,the membrane is non-porous. In certain implementations, the nasalcannula includes an outlet having a cross sectional area less than across sectional area of a patient's nostril.

In some implementations, the base unit further includes an oxygensensor. In certain implementations, the system includes an oxygensource. In some implementations, the system includes an oxygenconcentrator. In certain implementations, the oxygen source includes anoxygen outlet, the blower includes a blower inlet, and the oxygen outletis coupled to the blower inlet. In some implementations, the oxygenoutlet is coupled to the blower inlet by a needle valve. In certainimplementations, the blower includes a blower outlet, the liquidcontainer includes a liquid inlet and a liquid outlet, and the liquidinlet and the liquid outlet are each spaced from the blower outlet by atleast 10 cm.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 shows an illustrative respiratory therapy system;

FIG. 2 shows an illustrative respiratory therapy system including aliquid container configured to heat and circulate liquid;

FIG. 3 shows an isometric view of an illustrative liquid container for arespiratory therapy system;

FIG. 4 shows an isometric cut-away view of the illustrative liquidcontainer of FIG. 3;

FIG. 5 shows a top view of a component of the illustrative liquidcontainer of FIGS. 3 and 4;

FIG. 6 shows an illustrative feedback control system for heating liquidfor a respiratory therapy system;

FIG. 7 shows an illustrative system for blending air and oxygen forrespiratory therapy;

FIG. 8 shows an illustrative system for blending air and oxygen forerespiratory therapy using manually adjusted valves;

FIG. 9 shows an illustrative system for estimating the flow resistanceof a respiratory therapy system;

FIG. 10 shows an isometric view of an illustrative respiratory therapysystem for high velocity nasal insufflation;

FIG. 11 shows a front view of the illustrative respiratory therapysystem of FIG. 10;

FIG. 12 shows a side view of the illustrative respiratory therapy systemof FIGS. 10 and 11;

FIG. 13 shows a top view of the illustrative respiratory therapy systemof FIGS. 10-12;

FIG. 14 shows a rear isometric view of the illustrative respiratorytherapy system of FIGS. 10-12;

FIG. 15 shows a front view of an illustrative liquid container for arespiratory therapy system for high velocity nasal insufflation;

FIG. 16 shows a top view of the illustrative liquid container of FIG.15;

FIG. 17 shows a bottom view of the illustrative liquid container ofFIGS. 15 and 16;

FIG. 18 shows a cross-sectional view of the illustrative liquidcontainer of FIGS. 15-17 taken along section line A-A in FIG. 15;

FIG. 19 shows a front view of an illustrative connector for managing theflow of gas and liquid through a respiratory therapy system;

FIG. 20 shows a top view of the illustrative connector of FIG. 19;

FIG. 21 shows a cross-sectional view of the illustrative connector ofFIGS. 19 and 20 taken along section line A-A in FIG. 20;

FIG. 22 shows a cross-sectional view of another embodiment of theillustrative connector of FIGS. 19-21; and

FIG. 23 shows a perspective view of an illustrative respiratory therapysystem for high velocity nasal insufflation.

DETAILED DESCRIPTION

To provide an overall understanding of the systems, devices, and methodsdescribed herein, certain illustrative embodiments will be described.Although the embodiments and features described herein are specificallydescribed for use in connection with a high flow therapy system, it willbe understood that all the components and other features outlined belowmay be combined with one another in any suitable manner and may beadapted and applied to other types of respiratory therapy andrespiratory therapy devices, including mechanical ventilation,continuous positive airway pressure therapy (CPAP), oxygen masks,Venturi masks, low flow oxygen therapy, tracheotomy masks, and the like.

Systems, devices, and methods for humidifying a breathing gas arepresented. The system includes a base unit, a vapor transfer unit, anasal cannula, and a liquid container. The base unit includes a blower.The vapor transfer unit is external to the base unit and includes a gaspassage, a liquid passage, a gas outlet, and a membrane separating thegas passage and the liquid passage. The membrane permits transfer ofvapor into the gas passage from liquid in the liquid passage. The nasalcannula is coupled to the gas outlet of the vapor transfer unit. Theliquid container is configured to reversibly mate with the base unit.

The systems, devices, and methods presented herein have a low pressuresystem architecture which permits the system to be operated by a lowpressure source (e.g., <275 kPa, <200 kPa, <150 kPa, <100 kPa, <50 kPa,<30 kPa, <20 kPa, <10 kPa, or any other suitable gauge pressure). Insome implementations, the system is operated by a blower, such as acentrifugal blower. By using a blower or a similar low pressure source,the base unit does not require an external source of high pressure gas.Instead, the base unit can accept gas at ambient pressure and thenpressurize the gas (e.g., internally). This allows the base unit tofunction in environments in which pressurized gas sources are notavailable (e.g., at home, in an ambulance, and/or an outpatient carecenter). In some implementations, the low pressure gas source can acceptoxygen at a low pressure or at ambient pressure. This can enable the useof an oxygen concentrator rather than an oxygen tank.

The low pressure operation of the system is enabled at least in part bythe low flow resistance of the vapor transfer unit. For example, at aflow rate of 40 LPM, the flow resistance of the vapor transfer unit maybe <70 kPa, <60 kPa, <50 kPa, <40 kPa, <30 kPa, <25 kPa, <20 kPa, <15kPa, <10 kPa, <5 kPa, <4 kPa, <3 kPa, <2 kPa, <1 kPa, or any othersuitable flow resistance. Furthermore, in some implementations, thenasal cannula has a relatively short length and has separate flow pathsfor each nasal prong to lower the flow resistance of the system. Incertain implementations, to further reduce the flow resistance, thesystem uses a large bore delivery tube to carry the output breathing gasfrom the low pressure source to the vapor transfer unit. In someimplementations, the inner diameter of the delivery tube is more thanabout 5 mm. In certain implementations, the inner diameter of thedelivery tube is about 15 mm.

In certain implementations, the liquid container has a lower surfaceformed of a flexible film. In some implementations, the liquid containercouples to the base unit using a breech lock. A combination of breechlock and a lower surface formed of a flexible film may make inadvertentdisconnection of the liquid container more difficult during operation.This is because when liquid is in the liquid container, the liquidexerts pressure against the film, which in turn exerts pressure againstthe breech lock, causing friction. Friction makes the breech lock moreresistant to torque and thus more difficult to inadvertently disconnectduring operation.

In some implementations, the liquid is heated and circulated within theliquid container without contacting the base unit. This can permit thebase unit to be reused with lower risk of contamination compared toliquid-contacting base units.

In certain implementations the blower delivers breathing gas to the gaspassage of the vapor transfer unit via a delivery tube and the liquidcontainer delivers liquid to the liquid passage of the vapor transferunit via a liquid delivery line disposed within the delivery tube. (Theliquid container may also receive a return flow of liquid from the vaportransfer unit.) Since the delivery tube surrounds the liquid deliveryline, the delivery tube insulates the liquid delivery line from ambientair. The liquid delivery line may carry heated liquid, so insulating theline can reduce the energy required to maintain the temperature of theline and thus reduce the energy requirements of the system. Moreover,some of the heat that is “lost” from the liquid delivery line in thedelivery tube enters the flow of breathing gas. This warms the breathinggas, which later facilitates the transfer of vapor into the breathinggas at the vapor transfer unit. Thus, some of the heat “lost” from theliquid lines is still conserved within the breathing circuit.Additionally, in some implementations, the blower delivers heated gasthrough the delivery tube. In such implementations, the heated gas heatsthe liquid in the liquid delivery line, thus reducing the power demandon a liquid heater.

Furthermore, by permitting the delivery tube to surround the liquiddelivery line, the system reduces the number of separate tubes that mustbe managed by the user. In conventional respiratory therapy systems inwhich a liquid container is separate from a breathing gas source, theuser may have to manage two sets of tubes: tubes from the liquidcontainer to the humidifier as well as tubes from the breathing gassource to the humidifier. In a system according to certainimplementations disclosed herein, the gas path and the liquid path areintegrated within a single tube. This reduces the amount of spaceoccupied by tubing and reduces the risk of snagging the tubinginadvertently.

Additionally, disposing the liquid delivery line within the deliverytube reduces the risk of kinking the liquid delivery line or thedelivery tube. This is because the delivery tube shields the liquid linefrom kinking by increasing the minimum bend radius that the liquid lineundergoes during extreme bending. In some implementations, the deliverytube is corrugated to prevent or reduce kinking of the delivery tube orthe liquid line.

FIG. 1 shows an illustrative respiratory therapy system 100 according tosome implementations. The respiratory therapy system 100 includes a baseunit 102, a liquid container 130, a vapor transfer unit 112, and a nasalcannula 122. The base unit 102 includes a blower 104 and an uppersurface 138. The blower 104 includes an air inlet 148, which receivesambient air 106, and an oxygen inlet 150, which receives oxygen 108. Theblower 104 also includes a blower outlet 152, through which breathinggas 110 exits. The liquid container 130 includes a first liquid inlet144, a second liquid inlet 149, a liquid outlet 146, and a lower surface136. The liquid container 130 reversibly couples to the base unit 102 atan interface 134. The vapor transfer unit 112 includes a liquid passage114, a gas passage 116, a vapor transfer membrane 120, and a gas outlet118. The vapor transfer unit 112 is coupled to the gas outlet 152 by agas delivery tube 111. The nasal cannula 122 includes a nasal cannulabody 125 and nasal prongs 124 and 126.

The base unit 102 delivers output breathing gas 110 to the vaportransfer unit 112 using the blower 104. By using the blower 104, thebase unit 102 does not require an external source of pressurized gas.Instead, the base unit 102 can accept gas at ambient pressure. Thisallows the base unit 102 to function in environments in whichpressurized gas sources are not available (e.g., at home, in anambulance, and/or an outpatient care center). The base unit 102 is sizedfor convenient use in a variety of environments, including in a hospitalor at home. For example, in some implementations, the base unit 102 issized to sit on a conventional bed nightstand. In some implementations,the base unit 102 is configured to mount to an IV pole for use in ahealth care environment. The base unit 102 may be powered by a walloutlet, battery, other suitable power source, or any suitablecombination of power sources.

The blower 104 receives air 106 through the air inlet 148 and receivesoxygen 108 through the oxygen inlet 150. The blower 104 delivers outputbreathing gas 110 through the outlet 152. Although blending of oxygenand air is shown, in some implementations, the blower receives only air106. For example, certain patients may not require oxygen therapy oroxygen sources may be unavailable in some settings. Although the air 106and oxygen 108 are mixed within the blower 104 as depicted, in someimplementations the air 106 and the oxygen 108 are mixed upstream of theblower 104. In certain implementations, the air 106 and the oxygen 108are mixed downstream of the blower 104.

In some implementations, the blower 104 pressurizes the output breathinggas 110 to an output pressure that is lower than conventional wall airpressure (e.g., <275 kPa, <200 kPa, <150 kPa, <100 kPa, <50 kPa, <30kPa, <20 kPa, <10 kPa, or any other suitable gauge pressure). This lowpressure operation is enabled by the low pressure architecture of system100, in particular the relatively low resistance of the breathing gasdelivery tubing, vapor transfer unit 112, and nasal cannula 122, as willbe discussed further below. In certain implementations, the blower 104is a centrifugal blower.

The liquid container 130 delivers liquid (e.g., water) to the vaportransfer unit 112 through the liquid outlet 146. The liquid container130 receives new liquid 132 through the liquid inlet 144 and receivesrecirculated liquid 142 from the vapor transfer unit 112 through theliquid inlet 149. The liquid container 130 may include a pump fordriving the circulation of the liquid to and from the vapor transferunit 112. In certain implementations, the liquid container includes arotor which is driven by the base unit 102 to circulate the liquidwithin the liquid container. In certain implementations, the rotor isdriven by the base unit 102 by a magnetic coupling. In someimplementations, the circulation of the liquid may be driven by a pumpexternal to the liquid container 130.

In some implementations, the liquid container 130 heats the liquidwithin the liquid container 130. In such implementations, the heat maybe generated by the base unit 102 and communicated from the uppersurface 138 of the base unit to the lower surface 136 of the liquidcontainer 130. The lower surface 136 of the liquid container may beformed of a material with high thermal conductivity and/or of a thinmaterial. The lower surface 136 may be formed of a flexible film, whichmay improve the quality of contact of the lower surface 136 against theupper surface 138 compared to a rigid lower surface 136. In someimplementations, the lower surface 136 is a flexible polymer.

In certain implementations, the base unit 102 measures the amount ofliquid in the liquid container 130. In some implementations, the baseunit measures the amount of liquid in the liquid container 130 bymeasuring the pressure of the liquid in the liquid container 130. Thebase unit 102 may measure this pressure through a force sensor, pressuresensor, and/or strain sensor disposed on the upper surface 138 of thebase unit 102 which is in contact with the lower surface 136 of theliquid container 130. Although the liquid container 130 and the baseunit 102 are shown interfacing at the upper surface 138 of the base unit102 and the lower surface 136 of the liquid container 130, the skilledperson will appreciate that the liquid container 130 can interface withthe base unit 102 in other configurations. For example, in someimplementations, the liquid container 130 couples to a lateral side ofthe base unit 102.

The vapor transfer unit 112 receives the gas 110 from the blower 104 andthe liquid 140 from the liquid container 130 and delivers humidified gasthrough the gas outlet 118 to the nasal cannula 122. The gas 110received by the vapor transfer unit 112 travels through the gas passage116 before exiting the gas outlet 118. Simultaneously, the liquid 140circulates within the liquid passage 114. Some of the liquid 140diffuses across the vapor transfer membrane 120 and is converted tovapor 121. The vapor 121 is incorporated into the flow of gas 110through the gas passage 116. The remainder of the liquid 120 returns tothe liquid container 130 through the return path 142. In someimplementations, the liquid 140 is water. In such implementations, thegas 110 is humidified in the gas passage 116 by the vapor 121.

The gas passage 116 of the vapor transfer unit 112 provides a relativelylow flow resistance. For example, at a flow rate of 40 LPM, the flowresistance of gas through the vapor transfer unit 112 may be <70 kPa,<60 kPa, <50 kPa, <40 kPa, <30 kPa, <25 kPa, <20 kPa, <15 kPa, <10 kPa,<5 kPa, <4 kPa, <3 kPa, <2 kPa, <1 kPa, or any other suitable flowresistance. The low flow resistance of the vapor transfer unit 112 helpsenable the low pressure operation of the system 100, which in turnenables the system to driven by a blower rather than a high pressuresource.

The vapor transfer membrane 120 permits diffusion of the liquid 140through the membrane 120 from the liquid passage 114 to the gas passage116, where it becomes the vapor 121 and is absorbed into the gas 110flowing through the gas passage 116. In some implementations, the vaportransfer membrane 120 is non-porous. In certain implementations, thevapor transfer membrane 120 is porous. In some implementations, themembrane 120 is a thermoplastic elastomer, a block copolymer, apolyether block amide, or any other suitable polymer. Although only asingle vapor transfer membrane 120 is shown, in some implementations,the vapor transfer membrane 120 includes several membranes. For example,the vapor transfer membrane 120 may include a plurality of vaportransfer tubes or pleated sheets. Additional vapor transfer membranedesigns compatible with the present disclosure are described in U.S.patent application Ser. No. 14/675,198, the contents of which are herebyincorporated by reference in their entirety.

The vapor transfer unit 112 is configured to be positioned proximate tothe patient (e.g., within 10 feet, 6 feet, 3 feet, 2 feet, 1 foot, or 6inches or the patient's airway), so as to reduce the length of tubingthrough which the humidified air has to travel to reach the patient.Since the inner diameter of tubing carrying heated and humidified gasmust be relatively small to prevent condensation (e.g., 5 mm), reducingthe length that the heated and humidified gas must travel reduces thelength of the small diameter tubing. This reduces the resistance to airflow through the system, thereby enabling the system to operate at alower pressure.

The nasal cannula 122 receives humidified breathing gas from the gasoutlet 118 of the vapor transfer unit 112 and outputs the humidifiedbreathing gas 128 through the nasal prongs 124 and 126. The nasal prongs124 and 126 have a relatively small internal diameter to ensure arelatively high exit velocity of the breathing gas. In someimplementations, the internal diameter of the nasal prongs 124 and 126is <6 mm, <5 mm, <4 mm, <3 mm, <2 mm, or any other suitable diameter. Ahigh exit velocity allows the breathing gas to better flush carbondioxide from a patient's airways.

The nasal cannula 122 is configured to have a low flow resistance. Forexample, the nasal prong 124 and the nasal prong 126 each have separategas flow paths which do not collide at the nasal cannula body 125.Furthermore, in some implementations, the nasal cannula 122 has arelatively short length to lower the flow resistance of the nasalcannula 112. In certain implementations, the nasal cannula 112 has alength of <2.5 m, <2 m, <1.5 m, <1 m, <0.5 m, or any other suitablelength. Nasal cannula designs compatible with the present disclosure aredisclosed in U.S. patent application Ser. No. 13/665,100, the contentsof which are hereby incorporated by reference in their entirety.

To further reduce the flow resistance of the respiratory therapy system100, the delivery tube 111, which carries the output breathing gas 110from the blower 104 to the vapor transfer unit 112, has a relativelylarge inner diameter compared to conventional high flow therapy systems.In some implementations, the inner diameter of the delivery tube 111carrying the breathing gas 110 is more than about 5 mm. In certainimplementations, the inner diameter of the delivery tube 111 is about 15mm. This larger diameter delivery tube 111 further reduces the pressurerequired to operate the respiratory therapy system 100 by reducing majorhead losses.

By using a low resistance vapor transfer unit 112, nasal cannula 122,and delivery tube 111, the respiratory therapy system 100 enablesdelivery of high velocity, humidified breathing gas with a relativelylow pressure source, such as a blower (e.g., the blower 104). The use ofa low pressure source enables the use of the system 100 in a variety ofenvironments in which high pressure sources are not available (e.g., athome, in an ambulance, in an outpatient care facility).

FIG. 2 shows an illustrative respiratory therapy system 200, accordingto some implementations, including a liquid container 230 configured toheat and circulate liquid. FIG. 2 only depicts the path of liquid in thesystem 200. The skilled person will appreciate that the liquid heatingand circulation configuration depicted in FIG. 2 can be used with anysuitable breathing gas circuit, including the breathing gas circuitdisclosed in relation to FIG. 1.

The respiratory therapy system 200 includes a base unit 202 and theliquid container 230. The base unit 202 includes a motor 204, a driveshaft 206, a rotor 208, a recess 214, a mating surface 218, heatingplate portions 220 and 222, a pressure sensor 223, and a temperaturesensor 225. The rotor 208 has a rotational axis 216 and includes magnets210 and 212. The liquid container 230 includes a body 232, a matingsurface 224, cavities 244, 246, and 238, an inlet 240, an outlet 242, amembrane frit 248, an impeller 236, a magnet 250, a film 226, and arotor cup 252. The magnet 250 includes a north pole 254 and a south pole256.

The base unit 202 heats and circulates the liquid in the liquidcontainer 230. The base unit heats the liquid in the liquid containerusing the heater plate portions 220 and 222. In some implementations,the heater plate portions 220 and 222 are different portions of asingle, integral heater plate. The heater plate portions 220 and 222 arepositioned against the mating surface 218 of the base unit 202. Themating surface 218 of the base unit 202 mates with the mating surface224 of the liquid container 230. When the surfaces 218 and 224 aremated, the film 226 is positioned against the heater plate portions 220and 222. The film 226 may have high thermal conductivity. In someimplementations, the film 226 is flexible, which allows the film 226 toclosely conform to the surface of the heater 220 to improve heattransfer.

The base unit 202 circulates the liquid in the liquid container 230 by amagnetic coupling between the rotor 208 and the magnet 250. The rotor208 is driven by the motor 204 by the drive shaft 206. The rotor 208rotates the magnets 210 and 212 about the axis 216. The magnets 210 and212 are positioned in proximity to the recess 214. When the matingsurface 224 of the liquid container 230 mates with the mating surface218 of the base unit 202, the rotor cup 252 sits in the recess 214. Whenthe rotor cup 252 sits within the recess 214, the magnet 250magnetically couples with the magnets 210 and 212. The magnetic couplingbetween the magnet 250 and the magnets 210 and 212 enables the motor 204to transfer rotation to the magnet 250.

The magnet 250 is physically coupled to the impeller 236 so thatrotation of the magnet 250 results in rotation of the impeller 236. Theimpeller 236 is shaped so that rotation of the impeller 236 inducescirculation of liquid within the liquid container 230. Rotation of theimpeller 236 also draws in liquid 241 through the inlet 240 and into thecavity 238. While the liquid circulates within the liquid container 230,the membrane frit 248 allows gas trapped in the cavity 238 to escapeinto the atmosphere. Additionally, rotation of the impeller 236 movesliquid from the cavity 238 into the cavity 244 and then from the cavity244 to the cavity 246 along a path 245. While the liquid moves along thepath 245, it flows along the film 226. Since the film 226 is in contactwith the heating plates 220 and 222 during operation, the liquid isheated while moving along the path 245. The movement of the liquid alongthe path 245 may improve heat transfer by increasing heat convection.Rotation of the impeller 236 also moves liquid from the cavity 246 tothe outlet 242, where the liquid is expelled along a path 243. Theliquid may be allowed to circulate multiple times before exiting thecavities 244 and 246.

Over the course of operating the system 200, the liquid may gradually bedepleted as it is used to humidify breathing gas (not shown). Operatingthe system 200 with no liquid could lead to overheating. Accordingly, insome implementations, the base unit 202 senses when the liquid has beenor is about to be depleted. In certain implementations, the presence ofliquid in the liquid container 230 is sensed using the pressure sensor223. When the mating surface 224 of the liquid container 230 mates withthe mating surface 218 of the base unit 202, the film 226 sits againstthe pressure sensor 223. Since the film 226 is flexible, the pressuresensor can sense the pressure within the liquid container 230,particularly within the cavity 246, by measuring the deflection of thefilm 226. When the pressure measured at the film 226 drops, thisindicates that the water level has fallen. This information can be usedto shut off system 200 or to provide a warning to a user that the liquidcontainer 230 needs to be replenished. The pressure sensor can be astrain gauge, a MEMS sensor, a force transducer, a piezoelectric sensor,or any other suitable sensor or combination thereof. In certainimplementations, the absence or partial depletion of liquid can bedetected by the temperature sensor 225. For example, if water is used asthe liquid, the temperature sensor 225 may sense a steep rise intemperature (e.g., above the boiling point of water) when substantiallyall of the water is depleted. In some implementations, the pressuresensor 223 alerts the user when the force on the film 226 is low enoughto allow easy removal of the liquid container 230 from a base unit. Forexample, the pressure sensor 223 may alert the user when a torquerequired to disengage a breech lock between the liquid container 230 anda base unit are below a predefined threshold (e.g., 20 Nm, 10 Nm, 5 Nm,3 Nm, 2 Nm, 1 Nm, <1 Nm, or any other suitable threshold).

FIGS. 3-5 show an illustrative liquid container 300 for a respiratorytherapy system according to some implementations. FIG. 3 shows anisometric view of the liquid container 300, FIG. 4 shows an isometriccut-away view of the liquid container 300, and FIG. 5 shows a top viewof the body 302 of the liquid container 300 with the cover 304 removed.The liquid container 300 may be used in the respiratory therapy system100 of FIG. 1, the respiratory therapy system 200 of FIG. 2, or anyother suitable respiratory therapy system. The liquid container 200includes a body 302, a cover 304, a rotor cup 318, and a film 316. Thebody 302 includes breech lock tabs 305-310, a tubing port 312, an inlet314, a lower rim 317, and cavities 348, 340, and 346. As visible in FIG.5, the body 302 also includes a fluid inlet 324, a fluid outlet 326, andtubing paths 328 and 330. The rotor cup 318 includes a rim 319, a rotorcavity 320, and a bearing seat 322.

The liquid container 300 is depicted without tubing for clarity, butduring use the liquid container 300 includes two tubes: a first tubeconnected to the inlet 324 and a second tube connected to the outlet326. The first tube is held by the tubing path 328 and directs fluidalong a path 325. The second tube is held by the tubing path 330 anddirects fluid along a path 327.

The liquid container 300 receives liquid from a liquid source such as awater bag and then heats and circulates the liquid. The liquid container300 initially receives liquid at the inlet 314. The inlet 314 is influid communication with the cavities 338, 340, and 346. The cavities340 and 346 are bounded on the upper part by the body 302 and on thelower part by the film 316. The film 316 is joined in a fluid-tightmanner to the lower rim 317 of the body 302 and the rim 319 of the rotorcup 318. Liquid in the cavities 340 and 346 may receive heat conductedacross the film 316 by an external heater (e.g., heater plates 220 and222 of system 200). Liquid in the cavities 340 and 346 may be circulatedin the direction indicated by the arrow 341. This circulation may beinduced by a rotor (not shown) disposed within the rotor cavity 320(e.g., impeller 236 in system 200) or by any other suitable mechanism.The cavities 340 and 346 are also in fluid communication with the inlet324 and the outlet 326 (shown in FIG. 5). The inlet 324 receives liquidreturning from the vapor transfer unit (not shown) and passes suchliquid to the cavity 338 like the liquid received via the inlet 314. Thecirculated liquid is expelled through the outlet 326.

The liquid container 300 is configured to mate with a base unit (e.g.,the base unit 1002 of system 1000 of FIG. 10 below). To that end, thebody 302 includes the breech lock tabs 305-310. The breech lock tabs305-310 are disposed along the rim 317 of the body 302 and extendradially outward. The breech lock tabs 305-310 allow the liquidcontainer 300 to be locked to a base unit with a twisting motion andunlocked by a similar twisting motion in the opposite direction. Thebreech lock design allows for simple and quick attachment to a baseunit. Also, such an attachment mechanism is resistant to axial force,which may be developed by fluid pressure between the film 316 and thebase unit. Additionally, the breech lock design may make inadvertentdisconnection of the liquid container 300 more difficult duringoperation. This is because when liquid is in the cavities 340 and 346,the liquid exerts pressure against the film 316, which in turn exertspressure against the base unit (not shown), causing friction. Frictionmakes the breech lock more resistant to being twisted open. Thus, whenfluid is in the container 300 (i.e., during operation) the liquidcontainer 300 is more difficult to inadvertently disconnect from thebase unit.

The rotor cup 318 is dimensioned and configured to house a rotor forcirculating liquid within the liquid container 300. In someimplementations, the rotor cavity 320 of the rotor cup 318 houses amagnet for magnetically coupling with the base unit. The magnet mayrotate on a bearing seated on the bearing seat 322. The bearing may be aspherical bearing, a hydrostatic bearing, a journal bearing, or anyother suitable type of bearing.

By allowing liquid to be heated and circulated within the liquidcontainer 300, the liquid container can avoid exposing the components ofthe base unit to the liquid. This can permit the base unit to be reusedwith lower risk of contamination compared to liquid-contacting baseunits. Such a configuration makes disposal and replacement of the liquidcontainer 300 fairly simple.

FIG. 6 shows an illustrative feedback control system 600 for heatingliquid for a respiratory therapy system according to someimplementations. The feedback control system 600 includes a flexiblereservoir 602, a heater and heater substrate 604, a force sensor 606, atemperature sensor 608, a temperature sensor 610, and controller 612.The controller 612 receives a set point value 614. The set point value614 is a target temperature. Based on the set point value 614, thecontroller 612 generates a command value 616 and sends the commandsignal 616 to the heater and heater substrate 604. Upon receiving thecommand signal 616, the heater and heater substrate generate thermalenergy 618 which is applied to the flexible reservoir 602. As theflexible reservoir receives thermal energy the liquid within it heatsand the temperature of the flexible reservoir 602 increases. Thetemperature of the flexible reservoir 602 is measured by the temperaturesensor 610. This temperature 622 is sent to the controller 612.Additionally, the temperature of the heater and heater substrate 604 ismeasured by the temperature sensor 608 which sends this temperatureinformation to the controller 612 also. The controller 612 adjusts thecommand value 616 as necessary based on the temperature readings fromthe temperature sensor 608 and the temperature sensor 610. Thecontroller 612 may operate using any suitable control algorithm. Forexample, in some implementations, the controller 612 is a PIDcontroller. In certain implementations, the controller 612 is a simplehysteresis controller.

In addition to measuring temperature, the controller 612 also measuresthe pressure in the flexible reservoir 602. The controller 612 receivesa signal 626 from the force sensor 606 which is indicative of the force624 which is applied by the flexible reservoir on the force sensor 606.Measuring the pressure in the flexible reservoir 602 allows thecontroller 612 to determine the level of liquid (e.g., water) in theflexible reservoir. For example, the pressure measured by the forcesensor may be approximately linearly related to the level of water inthe flexible reservoir. According to the Bernoulli equation, thepressure of liquid at the bottom of a liquid column may be a function ofthe density of the liquid and the height of the liquid column. Theskilled person will appreciate that the force measured at the forcesensor 606 may be lower than the pressure in the flexible reservoir dueto the elasticity of the flexible reservoir 602 which may absorb some ofthe internal pressure. However, the skilled person will appreciate thatthe force sensor measurement 626 can be adjusted to account fordistortions due to the effect of the flexible reservoir 602 on thepressure measurement. Measuring the level of liquid in the flexiblereservoir 602 allows the system 600 to detect when liquid has beendepleted or is about to be depleted. Operating the system 600 with noliquid in the flexible reservoir 602 could lead to overheating anddamage to the system 600. Therefore, measuring the level of liquid 602can help avoid these unwanted outcomes.

The foregoing shows that the system 600 provides three layers ofprotection. First, the system 600 directly measures the heatertemperature using the temperature sensor 608. This allows the system todetect if the heater 604 is overheating. If the temperature sensor 608detects overheating of the heater 604, the controller 612 can send acommand signal 616 to shut off the heater and heater substrate 604. Inaddition, the temperature sensor 610 allows the temperature 620 of theflexible reservoir 602 to be measured. This allows the controller 612 todetect if the flexible reservoir 602 is being overheated. If theflexible reservoir 602 is overheated, the controller 612 can again senda command signal 616 to shut off or reduce the power supplied to theheater and heater substrate 604. Third, the force sensor 606 allows thecontroller 612 to sense when the liquid in the flexible reservoir 602has been depleted or is about to be depleted. This can also help avoidoverheating. Additionally, the measurement 626 of the force sensor 606allows the controller 612 to sense impending depletion of the flexiblereservoir 602 before it actually occurs. This can allow time to providea warning signal to a health care professional or user to replace liquidbefore any overheating occurs which could be detected by the temperaturesensor 608 and the temperature sensor 610. Thus, the force sensor 606complements the temperature sensors 608 and 610. The use of the forcesensor 606 to detect the fluid level is enabled by the use of theflexible reservoir 602. A rigid reservoir may make measurement of thefluid level in the reservoir more difficult using non-contact means.Some high-flow therapy systems use floats to determine the level ofliquid within a rigid reservoir. Such floats require more moving parts,which adds complexity and cost to the system. Furthermore, it ispossible for floats to become jammed and therefore erroneously indicatea higher than actual water level.

FIG. 7 shows an illustrative system 700 for blending air and oxygen forrespiratory therapy according to some implementations. The system 700includes an oxygen inlet 702, a needle valve 706, a blower 708, anoxygen sensor 710, a flow sensor 712, and a monitor 716. The oxygeninlet 702 feeds oxygen 704 to the needle valve 706. The oxygen inlet 702can receive oxygen from any suitable source. For example, the oxygeninlet 702 can receive oxygen from an oxygen tank or an oxygenconcentrator. Because the blower 708 is downstream from the oxygen inlet702, the oxygen inlet 702 can accept a relatively low pressure or evenambient pressure oxygen source. This enables the use of an oxygenconcentrator with the system 700. This is in contrast to someconventional high-flow therapy systems which require a high-pressureoxygen source. The oxygen 704 from the oxygen inlet 702 is fed to theneedle valve 706. The needle valve 706 controls the amount of oxygenthat is fed the blower 708 by allowing the flow resistance of the needlevalve 706 to be adjusted by the user. The blower 708 draws oxygen fromthe needle valve 706. The blower also draws ambient air 709. The oxygenand ambient air are mixed and pressurized in the blower 708. In someimplementations, the oxygen and air are mixed slightly upstream of theblower 708. In certain implementations, the oxygen and air are mixeddownstream of the blower 708. The gas output by the blower 708 is fedpast the oxygen sensor 710. The oxygen sensor senses the amount ofoxygen in the output gas from the blower 708 and sends this informationto the display 716. The oxygen measurement from the oxygen sensor 710can be displayed on the display 716 while the user is adjusting theneedle valve 706. This allows the user to have real-time feedback of theoxygen being delivered by the blower 708. This can allow for easyadjustment of the oxygen content and more precise adjustment of theoxygen content compared to conventional respiratory therapy systems.Conventional respiratory therapy systems relied on look up tables andmanual adjustment of air and oxygen sources to maintain a target flowrate and oxygen fraction. This required the user to refer to a table orperform mathematical calculations and vary two dials together. Thesystem 700 permits the user to set oxygen fraction using feedbackdisplayed on the display 716 rather than a look up table and allows theuser to adjust a single dial, namely the needle valve 706, to set thedesired oxygen fraction. After passing the oxygen sensor the gas outputof blower 708 passes the flow sensor 712. The flow sensor 712 also feedsto the display 716 so that the user can observe the flow rate. In theexample of FIG. 7, the output gas 714 has a temperature of 37° Celsius,a flow rate of 20 meters per minute, and an oxygen fraction of 35%. Themeasure of the flow sensor 712 can be used to automatically adjust thespeed of the blower 708 to maintain a constant flow rate set point.Since the blower 708 can be controlled by a feedback loop with the flowsensor 712, the blower 708 can be automatically controlled to maintainthe set flow rate. This allows the user who wants to change oxygenfraction to only consider oxygen fraction without also consideringchanges in the flow rate. Again, this allows independent control of theoxygen fraction apart from the flow rate. By enabling oxygen to becontrolled independently of flow rate in an easy fashion using thecombination of the needle valve 706, blower 708, oxygen sensor 710, flowsensor 712, and display 716, the system 700 enables a more convenientuser experience.

FIG. 8 shows an illustrative system for blending air and oxygen forrespiratory therapy using two manually-adjusted values according to someimplementations. While the system 700 involved adjusting a single valvemanually, the system 800 involves adjusting two valves to control flowrate and oxygen fraction. The system 800 includes a manually-adjustedair valve 814, a manually-adjusted oxygen valve 816, an air-oxygenblender 817, a flow sensor 804, an oxygen sensor 806, and a softwaredisplay system 802. The software display 802 includes an indicator ofdesired oxygen fraction 818, desired flow rate 820, suggested oxygenadjustment 822, and suggested air flow adjustment 824. The system 800accepts oxygen 812 through the manually-adjusted oxygen valve 816 andaccepts air 810 through the manually-adjusted air valve 814. The system800 outputs blended gas 808 for delivery to the patient. In use, a userwould enter the desired oxygen fraction 818 and desired flow rate 820into the software display 802. In response, the software display 802would indicate the necessary adjustments to the valves 814 and 816. Thisindication is made through the suggested oxygen flow adjustment 822 andthe suggested air flow adjustment 824. The suggested oxygen flowadjustment 822 uses the input desired oxygen fraction 818 and desiredflow rate 820 to generate an indication of the correct position of themanually-adjusted oxygen valve 816. The user would look to thesuggestion 822 and adjust the oxygen valve 816 accordingly.Additionally, the suggested air flow adjustment 824 instructs the userhow to manually adjust the air valve 814. The user would look to the airflow adjustment 824 to determine the correct position of the air valve814. When the oxygen valve 816 and the air valve 814 are set to thesuggested values 822 and 824, respectively, the output gas 808 shouldhave the desired properties indicated in 818 and 820. To insure that thecorrect oxygen fraction in air flow rate have been achieved, the flowrate sensor 804 and oxygen sensor 806 provide feedback information whichcan be used to determine whether the recommended adjustments 822 and 824need to be modified to actually achieve the desired properties 818 and820. Further oxygen blending configurations compatible with the presentdisclosure are described in U.S. patent application Ser. No. 14/983,212,the contents of which are hereby incorporated by reference in theirentirety.

FIG. 9 shows and illustrative system 900 for estimating the flowresistance of a respiratory therapy system according to someimplementations. The system 900 included a micro-controller 902, ablower 904, a flow sensor 906, a patient circuit 908, and a resistancecalculator 910. The micro-controller 902 uses a digital to analogconverter to output a command signal 912 to the blower 904. The blower904 includes a gas inlet 905. The blower 904 accepts gas at the gasinlet 905, pressurizes the gas, and outputs the pressurized gas as gasflow 914. The gas flow 914 is measured by the flow sensor 906. The flowrate information 915 is fed back to the micro-controller 902. The gasflow 916 exiting the flow sensor 906 enters the patient circuit 908. Thegas flow 918 exits the patient circuit 908 and flows to the patient. Thepatient circuit 908 may include a gas delivery tube and a nasal cannula.The resistance calculator 910 receives the digital to analog conversioncode 920, the flow sensor reading 922, and the error 924. From thesethree inputs, the resistance calculator 910 estimates the resistance ofthe patient circuit 908. The estimated resistance 926 is the output ofthe resistance calculator.

The estimated resistance 926 can be used to sense various conditions ofthe patient circuit 908. For example, the estimated resistance 926 canbe used to determine an obstruction of the patient circuit 908. If theestimated resistance is unusually high, this may indicate that thepatient circuit 908 is occluded. This occlusion could occur from thedelivery to being kinked. If the estimated resistance 926 is unusuallylow, this may indicate that the nasal cannula has been disconnected,that the delivery tube has been disconnected, or a similar malfunction.

FIGS. 10-14 show an illustrative respiratory therapy system 1000 forhigh velocity nasal insufflation according to some implementations. FIG.10 shows an isometric view of the respiratory therapy system 1000, FIG.11 shows a front view of the respiratory therapy system 1000, FIG. 12shows a side view of the respiratory therapy system 1000, FIG. 13 showsa top view of the respiratory therapy system 1000, and FIG. 14 shows arear isometric view of the respiratory therapy system 1000. Therespiratory therapy system 1000 includes a base unit 1002, a liquidcontainer 1050, a liquid line 1056, a delivery tube 1070, and a deliverytube connector 1004. The base unit 1002 includes a recess 1012,retention flanges 1030 a-f, a recess 1014, a retention tab 1016, anoxygen inlet 1032, an air inlet 1033, a front panel 1018, a display1020, a needle valve knob 1022, a pole mount 1024, and feet 1026 a-b.The liquid container 1050 includes a body 1052, and a cover 1054. Theliquid line 1056 includes a clip 1057. The delivery tube 1070 includesan upstream tube portion 1070 a, a downstream tube portion 1070 b, aliquid delivery line 1072, and a liquid return line 1074. The deliverytube connector 1004 includes a base 1010, an upstream connector 1006, adownstream connector 1008, and wings 1009 a-b.

The base unit 1002 is reversibly coupled to the liquid container 1050.The recess 1012 of the base unit 1002 accepts the body 1052 of theliquid container 1050. The recess 1014 of the base unit accepts theupstream portion 1070 a of the delivery tube 1070 so that the deliverytube 1070 can connect to the liquid container 1050 while the liquidcontainer 1050 is within the recess 1012. The retention flanges 1030 a-fmate with breech lock tabs (not visible) on the liquid container 1050 toretain the liquid container 1050 within the recess 1014. Similar to theretention flanges 1030 a-f, the retention tab 1016 mates with theupstream portion 1070 a of the delivery tube 1070 to retain the deliverytube 1070 within the recess 1014. The retention tab 1016 does not extendacross the entire recess 1014 so that the delivery tube 1070 can beremoved from the recess 1014 by rotating and lifting the liquidcontainer 1050 relative to the base unit 1002. In the implementation ofFIG. 10, such removal can be achieved by rotating the liquid container1050 counter clockwise. Although six retention flanges 1030 a-f aredepicted, any suitable number of retention flanges may be used (e.g., 1,2, 3, 4, 5, 7, 8, >8 or any other suitable number). In someimplementations, the liquid container 1050 is coupled to the base unitwithout the use of a breech lock configuration. For example, in certainimplementations, the liquid container 1050 slides linearly into the baseunit 1002 to interlock with the base unit. In certain implementations,the liquid container 1050 couples to the base unit 1002 by a frictionfit, an interference fit, a snap fit, a mechanical fastener, a magneticcoupling, or any other suitable coupling.

The base unit 1002 receives air and/or oxygen and outputs pressurizedgas. The base unit 1002 receives air through the air inlet 1033 and canreceive oxygen through the oxygen inlet 1032 (visible in FIG. 14). Thebase unit 1002 includes a blower (not visible), which pressurizes theair and/or oxygen within the base unit 1002. The air inlet 1033 canreceive ambient air at atmospheric pressure. The oxygen inlet 1032 canaccept oxygen at atmospheric pressure or at a higher pressure. Theoxygen inlet 1032 can accept oxygen from an oxygen concentrator.

The base unit 1002 allows the output of breathing gas to be controlledby a user via features of the front panel 1018. The front panel 1018 isangled slightly upward (best seen in FIG. 12). This allows a user toread and operate the front panel 1018 even when the base unit 1002 ispositioned at a relatively low height (e.g., on a bedside night stand)or at a relatively high height (e.g., on an IV pole). The base unit 1002can be supported by the feet 1026 a-b when sitting on a horizontalsurface, such as a night stand or other table. The base unit 1002 can besupported by the pole mount 1024 when mounted on an IV pole or any otherpole.

The front panel 1018 includes the display 1020 and the needle valve1022. In some implementations, the display 1020 is a touchscreen userinterface. In certain implementations, the display 1020 presents theflow rate of breathing gas output, the oxygen fraction of breathing gasoutput, the temperature of breathing gas output, the flow rate setpoint, the oxygen fraction set point, the temperature set point,overheating warnings, flow occlusion warnings, low flow resistancewarnings, liquid depletion warnings, and/or any other suitableinformation relevant to respiratory therapy.

The needle valve 1022 controls the amount of oxygen accepted through theoxygen inlet 1032. In some implementations, the needle valve 1022restricts the flow of oxygen when rotated counterclockwise and reducesresistance to the flow of oxygen when rotated clockwise. This canprovide an intuitive user interface even though such a direction ofrotation would be opposite conventional needle valves. In someimplementations, the needle valve 1022 can be used in conjunction withthe display 1020 to precisely control the oxygen fraction of thebreathing gas output. In particular, in some implementations, thedisplay 1020 shows the measured oxygen fraction of the output gas whilethe needle valve 1022 is being adjusted. This allows the user to adjustthe oxygen fraction in real time based on feedback from the display1020. A blower within the base unit 1002 may simultaneously becontrolled to maintain a target flow rate while oxygen is beingadjusted. For example, to maintain a constant flow rate, the blower maybe accelerated when oxygen input is decreased and may be deceleratedwhen the oxygen input is increased. Such a configuration allows a userto adjust oxygen fraction by adjusting a single variable, namelyresistance to oxygen flow, without having to separately account for thatvariable's effects on another flow parameter, namely overall flow rate.This simplifies the adjustment of the oxygen fraction of breathing gasoutput from the base unit 1002 and eliminates the need forsimultaneously, manually adjusting two variables using a look-up table.

The features of the liquid container 1050 facilitate its reversibleconnection to the base unit 1002. The liquid container 1050 includes thebody 1052 and the cover 1054. The cover 1054 serves as a handle forrotating, lifting, and/or inserting the body 1052 of the liquidcontainer 1050. The body 1052 is shaped to slide into the recess 1012 ofthe base unit 1002 and to be rotatable within the recess 1012. The body1052 includes a plurality of breech lock tabs (not visible) extendingradially outward which are disposed beneath the retention flanges 1030a-f. The breech lock tabs may press upward against the retention flanges1030 a-f when liquid is inside the liquid container 1050 if the liquidcontainer 1050 has a flexible lower surface (e.g., as in system 200) andif the liquid within the liquid container 1050 is above ambientatmospheric pressure. Pressure exerted by the breech lock tabs againstthe retention flanges 1030 a-f can increase friction against theretention flanges 1030 a-f which increases the torque required to rotatethe liquid container 1050 relative to the base unit 1002. This canprevent the liquid container 1050 from being inadvertently disconnectedfrom the base unit 1002 when liquid is in the liquid container 1050.

The liquid line 1056 delivers liquid to the liquid container 1050 from aliquid source. In some implementations, the liquid line 1056 deliversliquid from a flexible bag suspended above the liquid container 1050. Ifthe liquid source is sufficiently high above the liquid container 1050,the liquid line 1056 may deliver liquid at a pressure above ambientatmospheric pressure. The liquid line 1056 includes a clip 1057 whichcan be used to close the liquid line 1056 to prevent the communicationof fluid between the liquid container 1050 and the liquid line 1056.

The delivery tube 1070 delivers gas from the base unit 1002 and liquidfrom the liquid container 1050 to a vapor transfer unit (not shown). Thedelivery tube 1070 includes the upstream portion 1070 a and thedownstream portion 1070 b. The liquid delivery line 1072 and the liquidreturn line 1074 are disposed within the upstream portion 1070 a and thedownstream portion 1070 b of the delivery tube 1070. The upstreamportion 1070 a of the delivery tube 1070, the liquid delivery line 1072,and the liquid return line 1074 connect to the liquid container 1050.The liquid delivery line 1072 receives liquid from the liquid container1050 and directs the liquid toward the downstream portion 1070 b of thedelivery tube 1070 to the vapor transfer unit (not shown). The liquidreturn line 1074 receives liquid from the vapor transfer unit (notshown) and delivers the liquid to the liquid container 1050. Other thanthe liquid delivery line 1072 and the liquid return line 1074, the lumenof the upstream portion 1070 a of the delivery tube 1070 is not in fluidcommunication with the downstream portion 107 b of the delivery tube1070. This is because the breathing gas is introduced into the deliverytube 1070 at the downstream connector 1008, but not at the upstreamconnector 1060. The downstream portion 1070 b of the delivery tube 1070is connected to the downstream connector 1008 of the delivery tubeconnector 1004. The downstream portion 1070 b of the delivery tube 1070directs breathing gas output from the downstream connector 1008 to thevapor transfer unit (not shown) via the downstream portion 1070 b of thedelivery tube 1070.

To further reduce the flow resistance of the respiratory therapy system1000, the delivery tube 1070 has a relatively large inner diametercompared to conventional high flow therapy systems. In someimplementations, the inner diameter of the delivery tube 1070 is morethan about 5 mm. In certain implementations, the inner diameter of thedelivery tube 1070 is about 15 mm. This larger diameter delivery tube1070 further reduces the pressure required to operate the respiratorytherapy system 1000.

The liquid delivery line 1072 and the liquid return line 1074 aredisposed within the delivery tube 1070. Thus, the delivery tube 1070insulates the liquid delivery line 1072 and the liquid return line 1074from ambient air. The liquid in the liquid delivery line 1072 and theliquid return line 1074 is heated relative to the ambient air so thatthe liquid can be more easily converted to vapor at the vapor transferunit. Maintaining the elevated temperature of the liquid in the liquiddelivery line 1072 and the liquid return line 1074 requires a constantinput of thermal energy, but the insulation provided by the deliverytube 1070 can reduce the required energy input compared to a system inwhich the fluid is exposed to ambient air. Furthermore, heat that islost from the liquid delivery line 1072 and the liquid return line 1074in the downstream portion 1070 b of the delivery tube 1070 enters theflow of the breathing gas output of the base unit 1002. This warms thebreathing gas output, which can facilitate the transfer of vapor intothe breathing gas at the vapor transfer unit. Thus, some of the heat“lost” from the liquid delivery line 1072 and the liquid return line1074 in the downstream portion 1070 b is conserved within the breathingcircuit.

Disposing the liquid delivery line 1072 and the liquid return line 1074within the delivery tube 1070 also reduces the amount of tubing thatmust be managed by the user. In respiratory therapy systems in which aliquid container is separate from a breathing gas source, the user mayhave to manage two sets of tubes: tubes from the liquid container to thehumidifier as well as tubes from the breathing gas source to thehumidifier. In the system of the present disclosure, however, a singledelivery tube 1070 provides both liquid and gas to a vapor transferunit. This reduces the amount of space occupied by tubing and reducesthe risk of snagging the tubing inadvertently.

Furthermore, disposing the liquid delivery line 1072 and the liquidreturn line 1074 within the delivery tube 1070 reduces the risk ofkinking the liquid delivery line 1072, the liquid return line 1074, orthe delivery tube 1070. This arrangement reduces the risk of kinking andoccluding the delivery tube 1070 because the delivery tube 1070 shieldsthe liquid lines 1072 and 1074 from kinking by increasing the minimumbend radius that the liquid lines 1072 and 1074 undergo during extremebending. Moreover, in some implementations the delivery tube 1070 iscorrugated to prevent or reduce kinking of the delivery tube 1070.Corrugation of the delivery tube 1070 can also prevent or reduce kinkingof the liquid lines 1072 and 1074.

The delivery tube connector 1004 connects the delivery tube 1070 to thebase unit 1002. The delivery tube connector includes the base 1010, theupstream connector 1006, the downstream connector 1008, and the wings1009 a-b. The upstream connector 1006 connects to the upstream portion1070 a of the delivery tube 1070, and the downstream connector 1008connects to the downstream portion 1070 b of the delivery tube 1070 b.The upstream connector 1006 allows passage of the liquid lines 1072 and1074 into the downstream connector 1008, but does not otherwiseestablish fluid communication between the downstream connector 1006 andthe upstream connector 1008. The downstream connector 1008 establishesfluid communication between the breathing gas outlet (not shown) of thebase unit 1002 and the downstream portion 1070 b of the delivery tube1070.

The delivery tube connector 1004 is reversibly coupled to the base unit1002. The wings 1009 a-b connect to the base unit 1002 by extending intoa recess (not shown) on the side of the base unit 1002. The connectionbetween the wings 1009 a-b and the base unit 1002 is a snap fit. Incertain implementations, the connection between the wings 1009 a-b andthe base unit 1002 is a friction fit, a twist or screw connection, amagnetic coupling, J-slot, other slotted connection, or any othersuitable reversible coupling. The base 1010 of the delivery tubeconnector 1004 stabilizes the delivery tube connector 1004 against thebase unit 1002. In some implementations, the wings 1009 a-b and/or thebase 1010 of the delivery tube connector 1004 include features toprevent rotation of the base 1010 of the delivery tube connectorrelative to the base unit 1002. In certain implementations, theconnection between the delivery tube connector 1004 and the base unit1002 is designed such that the delivery tube connector 1004 willdisconnect from the base unit 1002 if the delivery tube 1070 is pulledsuddenly. This can prevent a user from inadvertently toppling the entirebase unit 1002 by accidently yanking the delivery tube 1070.

By enabling easy connection and disconnection between the base unit 1002and the liquid container 1050, the respiratory therapy system 1000facilitates periodic replacement of the liquid container 1050 andassociated liquid lines 1072 and 1074 to maintain sanitary operatingconditions. At the same time, the connection between the base unit 1002and the liquid container 1050 is secure enough to allow for stableoperation of the system 1000 and to prevent inadvertent disconnection ofthe liquid container 1050. Additionally, the integration of the liquidcontainer 1050 with the base unit 1020, along with the integration ofthe liquid lines 1072 and 1074 with the delivery tube 1070, simplifiesthe topology of the respiratory therapy system 1000. This facilitatesmanagement of tubing for the liquid and breathing gas paths, reduces therisk of kinking the liquid and breathing gas paths, and can conservethermal energy of the liquid lines 1072 and 1074.

FIGS. 15-18 show an illustrative liquid container 1500 for a respiratorytherapy system for high velocity nasal insufflation according to someimplementations. FIG. 15 shows a front view of the liquid container1500, FIG. 16 shows a top view of the liquid container 1500, FIG. 17shows a bottom view of the liquid container 1500, and FIG. 18 shows across-section of the liquid container 1500 taken along section line A-Ain FIG. 15. The liquid container 300 may be used in the respiratorytherapy system 100 of FIG. 1, the respiratory therapy system 200 of FIG.2, or any other suitable respiratory therapy system. The liquidcontainer 200 includes a body 1502, a cover 1504, a rotor cup 1518, afilm 1516, a liquid line 1556, and a clip 1557. The body 1502 includesbreech lock tabs 1505 a-f, a tubing port 1512, an inlet 1514, a lowerrim 1517, and cavities 1548, 1540, and 1546. The tubing port 1512includes a delivery path 1512 a and a return path 1512 b The rotor cup1518 includes a rotor 1515, rim 1519, a bearing 1523, and a bearing seat1522.

The liquid container 1500 is depicted without tubing for clarity, butduring use the liquid container 1500 includes two tubes: a first tubeconnected to the delivery path 1512 a to direct liquid out of the liquidcontainer 1500 and a second tube connected to the return path 1512 b todirect liquid into the liquid container 1500.

The liquid container 1500 receives liquid from a liquid source, such asa water bag, and then heats and circulates the liquid. The liquidcontainer 1500 initially receives liquid through the liquid line 1556 atthe inlet 1514. The inlet 1514 is in fluid communication with thecavities 1538, 1540, and 1546. The cavities 1540 and 1546 are bounded onthe upper part by the body 1502 and on the lower part by the film 1516.The film 1516 is joined in a fluid-tight manner to the lower rim 1517 ofthe body 1502 and the rim 1519 of the rotor cup 1518. Liquid in thecavities 1540 and 1546 may receive heat conducted across the film 1516by an external heater (e.g., heater plates 220 and 222 of system 200).Liquid in the cavities 1540 and 1546 may be circulated in the directionindicated by the arrow 1541. This circulation is induced by the rotor1515 disposed within the rotor cup 1518. In some implementations, therotor 1515 is an impeller, such as a radially delivering impeller. Incertain implementations, the rotor 1515 includes a magnet for beingmagnetically coupled to the base unit.

The cavities 1540 and 1546 are also in fluid communication with thereturn path 1512 b and the delivery path 1512 a (shown in FIG. 15). Thereturn path 1512 b receives liquid returning from the vapor transferunit (not shown) and passes such liquid to the cavity 1538 like theliquid received via the inlet 1514. The circulated liquid is expelledthrough an outlet (not shown).

The liquid container 1500 is configured to mate with a base unit (e.g.,the base unit 1002 of system 1000 of FIG. 10 above). To that end, thebody 1502 includes the breech lock tabs 1505 a-f. The breech lock tabs1505 a-f are disposed along the rim 1517 of the body 1502 and extendradially outward. The breech lock tabs 1505 a-f allow the liquidcontainer 1500 to be locked to a base unit with a twisting motion andunlocked by a similar twisting motion in the opposite direction. Thebreech lock design allows for simple and quick attachment to a baseunit. Also, such an attachment mechanism is resistant to axial force,which may be developed by fluid pressure between the film 1516 and thebase unit. Additionally, the breech lock design may make inadvertentdisconnection of the liquid container 1500 more difficult duringoperation. This is because when liquid is in the cavities 1540 and 1546,the liquid exerts pressure against the film 1516, which in turn exertspressure against the base unit (not shown), causing friction. Frictionmakes the breech lock more resistant to being twisted open. Thus, whenfluid is in the container 1500 (i.e., during operation) the liquidcontainer 1500 is more difficult to inadvertently disconnect from thebase unit.

The rotor cup 1518 is dimensioned and configured to house a rotor forcirculating liquid within the liquid container 1500. In someimplementations, the rotor cavity 1520 of the rotor cup 1518 houses amagnet for magnetically coupling with the base unit. The magnet mayrotate on a bearing seated on the bearing seat 1522. The bearing may bea spherical bearing, a hydrostatic bearing, a journal bearing, or anyother suitable type of bearing.

By allowing liquid to be heated and circulated within the liquidcontainer 1500, the liquid container can avoid exposing the componentsof the base unit to the liquid. This can permit the base unit to bereused with lower risk of contamination compared to liquid-contactingbase units. Such a configuration makes disposal and replacement of theliquid container 1500 fairly simple.

FIGS. 19-21 show an illustrative connector 1900 for managing the flow ofgas and liquid through a respiratory therapy system according to someimplementations. FIG. 19 shows a front view of the connector 1900, FIG.20 shows a top view of the connector 1900, and FIG. 21 shows across-section of the connector 1900 taken along section line A-A in FIG.20. The connector 1900 is coupled to an upstream delivery tube portion1970 a and a downstream delivery tube portion 1970 b. The connector 1900includes a body 1902, an upstream connector 1906, a downstream connector1908, wings 1909 a-b, snap hooks 1911 a-b, a breathing gas inlet 1947,an upstream lumen 1949, a breathing gas outlet 1951, and a barrier 1907.A liquid delivery line 1969 a and a liquid return line 1969 b passthrough the connector 1900. The connector 1900 may be connected to abreathing gas outlet of a high flow therapy system. For example, theconnector 1900 may be used in the system 1000 of FIG. 10 in place of thedelivery tube connector 1004.

The connector 1900 receives breathing gas in the breathing gas inlet1947 and directs the breathing gas toward the downstream delivery tubeportion 1970 b through the breathing gas outlet 1951 along the pathindicated by arrows 1950. Thus, the inlet 1947 and outlet 1951 are influid communication. The lumen 1949 is not in communication with eitherinlet 1947 or outlet 1951 because the barrier 1907 prevents thebreathing gas from travelling from the breathing gas inlet 1947 into theupstream lumen 1949. In some implementations, the breathing gas inlet1947 is connected to a blower outlet or a base unit gas outlet. Thedownstream delivery tube portion 1970 b connects to a vapor transferunit (not shown) and the upstream delivery tube portion 1970 a connectsto a source of heated fluid (not shown).

The connector 1900 also allows passage of liquid lines 1969 a-b from theupstream delivery tube portion 1970 a to the downstream delivery tubeportion 1970 b. Thus, liquid can travel across the connector 1900 in thedirection indicated by arrow 1952 (or in the opposite direction onreturn). The barrier 1907 includes two through holes to allow thepassage of the liquid delivery line 1969 a and the liquid return line1969 b. Since the upstream delivery tube portion 1970 a and thedownstream delivery tube portion 1970 b surround the liquid deliveryline 1969 a and the liquid return line 1969 b, the upstream deliverytube portion 1970 a and the downstream delivery tube portion 1970 binsulate the liquid delivery line 1969 a and the liquid return line 1969b from ambient air. The liquid delivery line 1969 a and the liquidreturn line 1969 b carry heated liquid, so insulating the lines 1969 aand 1969 b can reduce the energy required to maintain the temperature ofthe lines 1969 a and 1969 b and thus reduce the energy requirements ofthe system in which connector 1900 is used. Moreover, heat that is lostfrom the liquid delivery line 1069 a and the liquid return line 1069 bin the downstream delivery tube portion 1970 b enters the flow of thebreathing gas output. This warms the breathing gas output, which canfacilitate the transfer of vapor into the breathing gas at the vaportransfer unit (not shown). Thus, some of the heat “lost” from the liquidlines 1969 a-b in the downstream delivery tube portion 1970 b isconserved within the breathing circuit. Additionally, in someimplementations, the blower delivers heated gas through the deliverytube. In such implementations, the heated gas heats the liquid in theliquid delivery line, thus reducing the power demand on a liquid heater.

Furthermore, by permitting the upstream delivery tube portion 1970 a andthe downstream delivery tube portion 1970 b to surround the liquiddelivery line 1969 a and the liquid return line 1969 b, the connector1900 reduces the number of separate tubes that must be managed by theuser. In respiratory therapy systems in which a liquid container isseparate from a breathing gas source, the user may have to manage twosets of tubes: tubes from the liquid container to the humidifier as wellas tubes from the breathing gas source to the humidifier. In a systememploying the connector 1900, however, a gas path 1950 and two liquidlines 1969 a and 1969 b are all integrated within a single tube 1970 b.This reduces the amount of space occupied by tubing and reduces the riskof snagging the tubing inadvertently.

Additionally, disposing the liquid delivery line 1969 a and the liquidreturn line 1969 b within the downstream delivery tube portion 1970 breduces the risk of kinking the liquid delivery line 1969 a, the liquidreturn line 1969 b, or the downstream delivery tube portion 1970 b. Thisarrangement reduces the risk of kinking and occluding the downstreamdelivery tube portion 1970 b because the downstream delivery tubeportion 1970 b shields the liquid lines 1969 a-b from kinking byincreasing the minimum bend radius that the liquid lines 1969 a-bundergo during extreme bending. Moreover, in some implementations, thedelivery tube portions 1970 a-b are corrugated to prevent or reducekinking of the delivery tube portions 1970 a-b. Corrugation of thedelivery tube portions 1970 a-b can also prevent or reduce kinking ofthe liquid lines 1969 a-b.

The connector 1900 is configured to reversibly couple to a base unit orblower. The wings 1909 a-b are configured to connect to a base unit orblower using the snap hooks 1911 a-b. In some implementations, the body1902 is sized to fit within a bore or recess in a base unit or blowerand the snap hooks 1911 a-b are positioned to grab an internal edge ofthe bore or recess. In certain implementations, the connector 1900 isdecoupled from such a recess by pressing inwardly on the wings 1909 a-b.In certain implementations, the connection between the connector 1900and the base unit is a friction fit, a twist or screw connection, amagnetic coupling, J-slot, other slotted connection, or any othersuitable reversible coupling. In some implementations, the wings 1909a-b and/or the body 1902 of the connector 1900 include features toprevent the connector 1900 from rotating relative to the base unit. Incertain implementations, the connection between the connector 1900 andthe base unit is designed such that the connector 1900 will disconnectfrom the base unit if the either (or both) of the delivery tube portions1970 a-b is pulled suddenly. This can prevent a user from inadvertentlytoppling a base unit by accidently yanking the delivery tubeportions1970 a-b.

While FIG. 21 shows a connector having one gas inlet 1947, FIG. 22 showsa cross-sectional view of an illustrative connector 2000 for having twogas inlets according to some implementations. The connector 2000 iscoupled to an upstream delivery tube portion 2070 a and a downstreamdelivery tube portion 2070 b. The connector 2000 includes a body 2002,an upstream connector 2006, a downstream connector 2008, an auxiliaryport 2003, wings 2009 a-b, snap hooks 2011 a-b, a breathing gas inlet2047, an auxiliary inlet 2053, an upstream lumen 2049, a breathing gasoutlet 2051, and a barrier 2007. A liquid delivery line 2069 a and aliquid return line (not visible) pass through the connector 2000.

The auxiliary inlet 2003 is connected to a source of auxiliary gas,aerosol, or other fluid. In certain implementations, the auxiliary inlet2003 receives nebulized medicament from a nebulizer. Such nebulizedmedicament can be pumped into the auxiliary inlet 2003 or may be drawninto the auxiliary inlet 2003 by means of a Venturi effect created bythe flow of breathing gas along the path indicated by arrows 2050.Introducing medicament using the auxiliary inlet 2003 can simplifyadministration of medicament to the patient since medicament andbreathing gas can be inhaled simultaneously from a common userinterface. Also, since the auxiliary inlet 2003 is upstream from thehumidifier, there is negligible risk of the auxiliary inlet 2003 causingexcessive condensation compared to if the auxiliary inlet 2003 weredownstream of a humidifier.

The connector 2000 receives breathing gas in the breathing gas inlet2047 and directs the breathing gas toward the downstream delivery tubeportion 2070 b through the breathing gas outlet 2051 along the pathindicated by arrows 2050. Thus, the inlet 2047 and outlet 2051 are influid communication. The lumen 2049 is not in communication with eitherinlet 2047 or outlet 2051 because the barrier 2007 prevents thebreathing gas from travelling from the breathing gas inlet 2047 into theupstream lumen 2049. In some implementations, the breathing gas inlet2047 of the connector 2000 is connected to a breathing gas outlet of ahigh flow therapy system. For example, the connector 2000 may be used inthe system 1000 of FIG. 10 in place of the delivery tube connector 1004.The downstream delivery tube portion 2070 b connects to a vapor transferunit (not shown) and the upstream delivery tube portion 2070 a connectsto a source of heated fluid (not shown).

The connector 2000 also allows passage of liquid lines 2069 a-b from theupstream delivery tube portion 2070 a to the downstream delivery tubeportion 2070 b. Thus, liquid can travel across the connector 2000 in thedirection indicated by arrow 2052 (or in the opposite direction onreturn). The barrier 2007 includes two through holes to allow thepassage of the liquid delivery line 2069 a and the liquid return line2069 b. Since the upstream delivery tube portion 2070 a and thedownstream delivery tube portion 2070 b surround the liquid deliveryline 2069 a and the liquid return line 2069 b, the upstream deliverytube portion 2070 a and the downstream delivery tube portion 2070 binsulate the liquid delivery line 2069 a and the liquid return line 2069b from ambient air. The liquid delivery line 2069 a and the liquidreturn line 2069 b carry heated liquid, so insulating the lines 2069 aand 2069 b can reduce the energy required to maintain the temperature ofthe lines 2069 a and 2069 b and thus reduce the energy requirements ofthe system in which connector 2000 is reduced. Moreover, heat that islost from the liquid delivery line 1069 a and the liquid return line1069 b in the downstream delivery tube portion 2070 b enters the flow ofthe breathing gas output. This warms the breathing gas output as well asthe fluid introduced by the auxiliary inlet 2003, thereby facilitatingthe transfer of vapor into the gas at the vapor transfer unit (notshown). Thus, some of the heat “lost” from the liquid lines 2069 a-b inthe downstream delivery tube portion 2070 b is conserved within thebreathing circuit.

Furthermore, by permitting the upstream delivery tube portion 2070 a andthe downstream delivery tube portion 2070 b to surround the liquiddelivery line 2069 a and the liquid return line 2069 b, the connector2000 reduces the number of separate tubes that must be managed by theuser. In respiratory therapy systems in which a liquid container isseparate from a breathing gas source, the user may have to manage twosets of tubes: tubes from the liquid container to the humidifier as wellas tubes from the breathing gas source to the humidifier. In a systememploying the connector 2000, however, a gas path 2050 and two liquidlines 2069 a and 2069 b are all integrated within a single tube 2070 b.This reduces the amount of space occupied by tubing and reduces the riskof snagging the tubing inadvertently.

Additionally, disposing the liquid delivery line 2069 a and the liquidreturn line 2069 b within the downstream delivery tube portion 2070 breduces the risk of kinking the liquid delivery line 2069 a, the liquidreturn line 2069 b, or the downstream delivery tube portion 2070 b. Thisarrangement reduces the risk of kinking and occluding the downstreamdelivery tube portion 2070 b because the downstream delivery tubeportion 2070 b shields the liquid lines 2069 a-b from kinking byincreasing the minimum bend radius that the liquid lines 2069 a-bundergo during extreme bending. Moreover, in some implementations, thedelivery tube portions 2070 a-b are corrugated to prevent or reducekinking of the delivery tube portions 2070 a-b. Corrugation of thedelivery tube portions 2070 a-b can also prevent or reduce kinking ofthe liquid lines 2069 a-b.

The connector 2000 is configured to reversibly couple to a base unit orblower. The wings 2009 a-b are configured to connect to a base unit orblower using the snap hooks 2011 a-b. In some implementations, the body2002 is sized to fit within a bore or recess in a base unit or blowerand the snap hooks 2011 a-b are positioned to grab an internal edge ofthe bore or recess. In certain implementations, the connector 2000 isdecoupled from such a recess by pressing inwardly on the wings 2009 a-b.In certain implementations, the connection between the connector 2000and the base unit is a friction fit, a twist or screw connection, amagnetic coupling, J-slot, other slotted connection, or any othersuitable reversible coupling. In some implementations, the wings 2009a-b and/or the body 2002 of the connector 2000 include features toprevent the connector 2000 from rotating relative to the base unit. Incertain implementations, the connection between the connector 2000 andthe base unit is designed such that the connector 2000 will disconnectfrom the base unit if the either (or both) of the delivery tube portions2070 a-b is pulled suddenly. This can prevent a user from inadvertentlytoppling a base unit by accidently yanking the delivery tube portions2070 a-b.

By introducing medicament using the auxiliary inlet 2003, the connector2000 can simplify administration of medicament to the patient. Sincemedicament and breathing gas can be inhaled simultaneously from a commonuser interface, a patient may enjoy increased comfort which may lead toincreased compliance. Also, since the auxiliary inlet 2003 is upstreamfrom the humidifier, there is negligible risk of the auxiliary inlet2003 causing excessive condensation compared to if the auxiliary inlet2003 were downstream of a humidifier.

FIG. 23 shows a perspective view of an illustrative respiratory therapysystem 2300 for high velocity nasal insufflation according to someimplementations. The respiratory therapy system 2300 includes a baseunit 2302, a liquid container 2350, a liquid line 2356, a delivery tube2370, a delivery tube connector 2304, a vapor transfer unit 2380, and anasal cannula 2390. The base unit 2302 includes a recess 2312,a recess2314, a retention tab 2316, a front panel 2318, a display 2320, a needlevalve knob 2322, a pole mount (not visible), and feet (not visible). Theliquid container 2350 includes a body 2352, and a cover 2354. Thedelivery tube 2370 includes an upstream tube portion 2370 a, adownstream tube portion 2370 b, a liquid delivery line (not visible),and a liquid return line (not visible). The delivery tube connector 2304includes a base 2310, an upstream connector 2306, a downstream connector2308, and wings (not visible).

The base unit 2302 is reversibly coupled to the liquid container 2350.The recess 2312 of the base unit 2302 accepts the body 2352 of theliquid container 2350. The recess 2314 of the base unit accepts theupstream portion 2370 a of the delivery tube 2370 so that the deliverytube 2370 can connect to the liquid container 2350 while the liquidcontainer 2350 is within the recess 2312. The retention tab 2316 mateswith the upstream portion 2370 a of the delivery tube 2370 to retain thedelivery tube 2370 within the recess 2314. The retention tab 2316 doesnot extend across the entire recess 2314 so that the delivery tube 2370can be removed from the recess 2314 by rotating and lifting the liquidcontainer 2350 relative to the base unit 2302. In the implementation ofFIG. 23, such removal can be achieved by rotating the liquid container2350 counter clockwise. In some implementations, the recess 2314includes retention flanges which mate with breech lock tabs on theliquid container 2350 to retain the liquid container 2350 within therecess 2314. Any suitable number of retention flanges may be used (e.g.,1, 2, 3, 4, 5, 6, 7, 8, >8 or any other suitable number). In someimplementations, the liquid container 2350 is coupled to the base unitwithout the use of a breech lock configuration. For example, in certainimplementations, the liquid container 2350 slides linearly into the baseunit 2302 to interlock with the base unit. In certain implementations,the liquid container 2350 couples to the base unit 2302 by a frictionfit, an interference fit, a snap fit, a mechanical fastener, a magneticcoupling, or any other suitable coupling.

The base unit 2302 receives air and/or oxygen and outputs pressurizedgas. The base unit 2302 receives air through an air inlet and canreceive oxygen through an oxygen inlet. The base unit 2302 includes ablower (not visible), which pressurizes the air and/or oxygen within thebase unit 2302. The air inlet can receive ambient air at atmosphericpressure. The oxygen inlet can accept oxygen at atmospheric pressure orat a higher pressure. The oxygen inlet can accept oxygen from an oxygenconcentrator.

The base unit 2302 allows the output of breathing gas to be controlledby a user via features of the front panel 2318. The front panel 2318 isangled slightly upward. This allows a user to read and operate the frontpanel 2318 even when the base unit 2302 is positioned at a relativelylow height (e.g., on a bedside night stand) or at a relatively highheight (e.g., on an IV pole). The base unit 2302 can be supported byfeet (not shown) when sitting on a horizontal surface, such as a nightstand or other table. The base unit 2302 can be supported by a polemount (not shown) when mounted on an IV pole or any other pole.

The front panel 2318 includes the display 2320 and the needle valve2322. In some implementations, the display 2320 is a touchscreen userinterface. In certain implementations, the display 2320 presents theflow rate of breathing gas output, the oxygen fraction of breathing gasoutput, the temperature of breathing gas output, the flow rate setpoint, the oxygen fraction set point, the temperature set point,overheating warnings, flow occlusion warnings, low flow resistancewarnings, liquid depletion warnings, and/or any other suitableinformation relevant to respiratory therapy.

The needle valve 2322 controls the amount of oxygen accepted by the baseunit 2302. In some implementations, the needle valve 2322 restricts theflow of oxygen when rotated counterclockwise and reduces resistance tothe flow of oxygen when rotated clockwise. This can provide an intuitiveuser interface even though such a direction of rotation would beopposite conventional needle valves. In some implementations, the needlevalve 2322 is used in conjunction with the display 2320 to preciselycontrol the oxygen fraction of the breathing gas output. In particular,in some implementations, the display 2320 shows the measured oxygenfraction of the output gas while the needle valve 2322 is beingadjusted. This allows the user to adjust the oxygen fraction in realtime based on feedback from the display 2320. A blower within the baseunit 2302 may simultaneously be controlled to maintain a target flowrate while oxygen is being adjusted. For example, to maintain a constantflow rate, the blower may be accelerated when oxygen input is decreasedand may be decelerated when the oxygen input is increased. Such aconfiguration allows a user to adjust oxygen fraction by adjusting asingle variable, namely resistance to oxygen flow, without having toseparately account for that variable's effects on another flowparameter, namely overall flow rate. This simplifies the adjustment ofthe oxygen fraction of breathing gas output from the base unit 2302 andeliminates the need for simultaneously, manually adjusting two variablesusing a look-up table.

The features of the liquid container 2350 facilitate its reversibleconnection to the base unit 2302. The liquid container 2350 includes thebody 2352 and the cover 2354. The cover 2354 serves as a handle forrotating, lifting, and/or inserting the body 2352 of the liquidcontainer 2350. The body 2352 is shaped to slide into the recess 2312 ofthe base unit 2302 and to be rotatable within the recess 2312. The body2352 may include a plurality of breech lock tabs extending radiallyoutward which are disposed beneath the retention flanges. The breechlock tabs may press upward against retention flanges when liquid isinside the liquid container 2350 if the liquid container 2350 has aflexible lower surface (e.g., as in system 200) and if the liquid withinthe liquid container 2350 is above ambient atmospheric pressure.Pressure exerted by the breech lock tabs against the retention flangescan increase friction against the retention flanges which increases thetorque required to rotate the liquid container 2350 relative to the baseunit 2302. This can prevent the liquid container 2350 from beinginadvertently disconnected from the base unit 2302 when liquid is in theliquid container 2350.

The liquid line 2356 delivers liquid to the liquid container 2350 from aliquid source. In some implementations, the liquid line 2356 deliversliquid from a flexible bag suspended above the liquid container 2350. Ifthe liquid source is sufficiently high above the liquid container 2350,the liquid line 2356 may deliver liquid at a pressure above ambientatmospheric pressure. The liquid line 2356 may include a clip which canbe used to close the liquid line 2356 to prevent the communication offluid between the liquid container 2350 and the liquid line 2356.

The delivery tube 2370 delivers gas from the base unit 2302 and liquidfrom the liquid container 2350 to the vapor transfer unit 2380. Thedelivery tube 2370 includes the upstream portion 2370 a and thedownstream portion 2370 b. The liquid delivery line (not visible) andthe liquid return line (not visible) are disposed within the upstreamportion 2370 a and the downstream portion 2370 b of the delivery tube2370. The upstream portion 2370 a of the delivery tube 2370, the liquiddelivery line, and the liquid return line connect to the liquidcontainer 2350. The liquid delivery line receives liquid from the liquidcontainer 2350 and directs the liquid toward the downstream portion 2370b of the delivery tube 2370 to the vapor transfer unit 2380. The liquidreturn line receives liquid from the vapor transfer unit 2380 anddelivers the liquid to the liquid container 2350. Other than the liquiddelivery line and the liquid return line, the lumen of the upstreamportion 2370 a of the delivery tube 2370 is not in fluid communicationwith the downstream portion 2370 b of the delivery tube 2370. This isbecause the breathing gas is introduced into the delivery tube 2370 atthe downstream connector 2308, but not at the upstream connector 2360.The downstream portion 2370 b of the delivery tube 2370 is connected tothe downstream connector 2308 of the delivery tube connector 2304. Thedownstream portion 2370 b of the delivery tube 2370 directs breathinggas output from the downstream connector 2308 to the vapor transfer unit2380 via the downstream portion 2370 b of the delivery tube 2370.

To further reduce the flow resistance of the respiratory therapy system2300, the delivery tube 2370 has a relatively large inner diametercompared to conventional high flow therapy systems. In someimplementations, the inner diameter of the delivery tube 2370 is morethan about 5 mm. In certain implementations, the inner diameter of thedelivery tube 2370 is about 15 mm. This larger diameter delivery tube2370 further reduces the pressure required to operate the respiratorytherapy system 2300.

The liquid delivery line and the liquid return line are disposed withinthe delivery tube 2370. Therefore, the delivery tube 2370 insulates theliquid delivery line and the liquid return line from ambient air. Theliquid in the liquid delivery line and the liquid return line is heatedrelative to the ambient air so that the liquid can be more easilyconverted to vapor at the vapor transfer unit 2380. Maintaining theelevated temperature of the liquid in the liquid delivery line and theliquid return line requires a constant input of thermal energy, but theinsulation provided by the delivery tube 2370 can reduce the requiredenergy input compared to a system in which the fluid is exposed toambient air. Furthermore, heat that is lost from the liquid deliveryline and the liquid return line in the downstream portion 2370 b of thedelivery tube 2370 enters the flow of the breathing gas output of thebase unit 2302. This warms the breathing gas output, which canfacilitate the transfer of vapor into the breathing gas at the vaportransfer unit 2380. Thus, some of the heat “lost” from the liquiddelivery line and the liquid return line in the downstream portion 2370b is conserved within the breathing circuit.

Disposing the liquid delivery line and the liquid return line within thedelivery tube 2370 also reduces the amount of tubing that must bemanaged by the user. In respiratory therapy systems in which a liquidcontainer is separate from a breathing gas source, the user may have tomanage two sets of tubes: tubes from the liquid container to thehumidifier as well as tubes from the breathing gas source to thehumidifier. In the system of the present disclosure, however, a singledelivery tube 2370 provides both liquid and gas to the vapor transferunit 2380. This reduces the amount of space occupied by tubing andreduces the risk of snagging the tubing inadvertently.

Furthermore, disposing the liquid delivery line and the liquid returnline within the delivery tube 2370 reduces the risk of kinking theliquid delivery line, the liquid return line, or the delivery tube 2370.This arrangement reduces the risk of kinking and occluding the deliverytube 2370 because the delivery tube 2370 shields the liquid lines fromkinking by increasing the minimum bend radius that the liquid linesundergo during extreme bending. Moreover, the delivery tube 2370 iscorrugated to prevent or reduce kinking of the delivery tube 2370.Corrugation of the delivery tube 2370 can also prevent or reduce kinkingof the liquid lines.

The delivery tube connector 2304 connects the delivery tube 2370 to thebase unit 2302. The delivery tube connector includes the base 2310, theupstream connector 2306, the downstream connector 2308, and the wings.The upstream connector 2306 connects to the upstream portion 2370 a ofthe delivery tube 2370, and the downstream connector 2308 connects tothe downstream portion 2370 b of the delivery tube 2370 b. The upstreamconnector 2306 allows passage of the liquid lines into the downstreamconnector 2308, but does not otherwise establish fluid communicationbetween the downstream connector 2306 and the upstream connector 2308.The downstream connector 2308 establishes fluid communication betweenthe breathing gas outlet of the base unit 2302 and the downstreamportion 2370 b of the delivery tube 2370.

The delivery tube connector 2304 is reversibly coupled to the base unit2302. The connector 2304 connects to the base unit 2302 by extendinginto a recess (not shown) on the side of the base unit 2302. In someimplementations, the connection between the connector 2304 and the baseunit 2302 is a snap fit. In certain implementations, the connectionbetween the connector 2304 and the base unit 2302 is a friction fit, atwist or screw connection, a magnetic coupling, J-slot, other slottedconnection, or any other suitable reversible coupling. The base 2310 ofthe delivery tube connector 2304 stabilizes the delivery tube connector2304 against the base unit 2302. In some implementations, the deliverytube connector 2304 includes features to prevent rotation of the base2310 of the delivery tube connector relative to the base unit 2302. Incertain implementations, the connection between the delivery tubeconnector 2304 and the base unit 2302 is designed such that the deliverytube connector 2304 will disconnect from the base unit 2302 if thedelivery tube 2370 is pulled suddenly. This can prevent a user frominadvertently toppling the entire base unit 2302 by accidently yankingthe delivery tube 2370.

By enabling easy connection and disconnection between the base unit 2302and the liquid container 2350, the respiratory therapy system 2300facilitates periodic replacement of the liquid container 2350 andassociated liquid lines to maintain sanitary operating conditions. Atthe same time, the connection between the base unit 2302 and the liquidcontainer 2350 is secure enough to allow for stable operation of thesystem 2300 and to prevent inadvertent disconnection of the liquidcontainer 2350. Additionally, the integration of the liquid container2350 with the base unit 2320, along with the integration of the liquidlines with the delivery tube 2370, simplifies the topology of therespiratory therapy system 2300. This facilitates management of tubingfor the liquid and breathing gas paths, reduces the risk of kinking theliquid and breathing gas paths, and can conserve thermal energy of theliquid lines.

The vapor transfer unit 2380 receives gas from the base unit 2302 andliquid from the liquid container 2350 and delivers humidified gasthrough the gas outlet 118 to the nasal cannula 122. Gas received by thevapor transfer unit 2380 travels through a gas passage (not visible)before exiting the gas outlet 2384. In the gas passage, the gas ishumidified by vapor. In some implementations, the vapor transfer unit2380 includes a membrane that permits diffusion of liquid through themembrane from the liquid passage (not visible) to the gas passage, wherethe liquid becomes a vapor and is incorporated into the gas flow.Simultaneously, liquid may circulate within the liquid passage. Theremainder of the liquid may return to the liquid container 2350 throughthe return liquid line within the delivery tube 2370. The gas passagewithin the vapor transfer unit 2380 provides a relatively low flowresistance. For example, at a flow rate of 40 LPM, the flow resistanceof the vapor transfer unit 2380 may be <70 kPa, <60 kPa, <50 kPa, <40kPa, <30 kPa, <25 kPa, <20 kPa, <15 kPa, <10 kPa, <5 kPa, <4 kPa, <3kPa, <2 kPa, <1 kPa, or any other suitable flow resistance. The low flowresistance of the vapor transfer unit 2380 helps enable the low pressureoperation of the system 2300, which in turn enables the system to drivenby a blower rather than a high pressure source.

The vapor transfer membrane may be a non-porous membrane that allows thepassage of water vapor. In some implementations, the membrane is Pebaxor any other suitable polymer. In some implementations, the vaportransfer unit includes several vapor transfer membranes. For example,the vapor transfer unit may include a plurality of vapor transfer tubesor pleated sheets. Further vapor transfer membrane designs compatiblewith the present disclosure are described in U.S. patent applicationSer. Nos. 14/675,198 and 14/983,225, the contents of which are herebyincorporated by reference in their entirety.

The vapor transfer unit 2380 is configured to be positioned proximate tothe patient (e.g., within 10 feet, 6 feet, 3 feet, 2 feet, 1 foot, or 6inches or the patient's airway), so as to reduce the length of tubingthrough which the humidified air has to travel to reach the patient.Since the diameter of tubing carrying heated and humidified gas must berelatively small to prevent condensation (e.g., 5 mm ID), reducing thelength that the heated and humidified gas must travel reduces the lengthof the small diameter tubing. This reduces the resistance to air flowthrough the system, thereby enabling the system to operate at a lowerpressure.

The nasal cannula 2390 receives humidified breathing gas from the gasoutlet 2370 of the vapor transfer unit 2380 and outputs the humidifiedbreathing gas through the nasal prongs 2394 a and 2394 b. The nasalprongs 2394 a-b have a relatively small internal diameter to ensure arelatively high exit velocity of the breathing gas. In someimplementations, the internal diameter of the nasal prongs 2394 a-b is<6 mm, <5 mm, <4 mm, <3 mm, <2 mm, or any other suitable diameter. Ahigh exit velocity allows the breathing gas to better flush carbondioxide from a patient's airways.

The nasal cannula 2390 is configured to have a low flow resistance. Forexample, the nasal prong 2394 a and the nasal prong 2394 b each haveseparate gas flow paths which do not collide at the nasal cannula body2395. Furthermore, in some implementations, the nasal cannula 2390 has arelatively short length to lower the flow resistance of the nasalcannula 2390. In certain implementations, the nasal cannula 2390 has alength of <2.5 m, <2 m, <1.5 m, <1 m, <0.5 m, or any other suitablelength. Nasal cannula designs compatible with the present disclosure aredisclosed in U.S. patent application Ser. No. 13/665,100 and U.S.Provisional Patent Application No. 62/555,945, the contents of which arehereby incorporated by reference in their entirety.

By using a low resistance vapor transfer unit 2380, nasal cannula 2390,and delivery tube 2370, the respiratory therapy system 2300 enablesdelivery of high velocity, humidified breathing gas with a relativelylow pressure source, such as a blower. The use of a low pressure sourceenables the use of the system 2300 in a variety of environments in whichhigh pressure sources are not available (e.g., at home, in an ambulance,in an outpatient care facility).

The foregoing is merely illustrative of the principles of thedisclosure, and the systems, devices, and methods can be practiced byother than the described embodiments, which are presented for purposesof illustration and not of limitation. It is to be understood that thesystems, devices, and methods disclosed herein, while shown for use inhigh flow therapy and mechanical ventilation systems, may be applied tosystems, devices, and methods to be used in other ventilation circuits.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

1. A system for delivering breathing gas, the system comprising: a baseunit comprising a blower; a vapor transfer unit external to the baseunit and comprising: a gas passage, a liquid passage, a gas outlet, anda membrane separating the gas passage and the liquid passage, whereinthe membrane permits transfer of vapor into the gas passage from liquidin the liquid passage; a nasal cannula coupled to the gas outlet; and aliquid container configured to reversibly mate with the base unit. 2.The system of claim 1, wherein the liquid container interlocks with asurface of the base unit.
 3. The system of claim 1, wherein thecontainer has a surface formed of a flexible film
 4. The system of claim1, wherein the base unit further comprises a heating element for heatingliquid, the heating element having a heating surface.
 5. The system ofclaim 1, wherein the flexible film is configured to mate with theheating surface when the liquid container mates with the base unit. 6.The system of claim 1, wherein the blower is configured to pressurizebreathing gas to less than about 276 kPa (40 psi).
 7. The system ofclaim 1, wherein the liquid container includes an impeller.
 8. Thesystem of claim 1, wherein the base unit includes a motor.
 9. The systemof claim 8, wherein the motor is magnetically coupled to impeller. 10.The system of claim 1, wherein the liquid passage is coupled to theliquid container by a first tube.
 11. The system of claim 1, wherein thegas passage is coupled to the blower by a second tube.
 12. The system ofclaim 11, wherein the first tube passes within the second tube.
 13. Thesystem of claim 1, wherein base unit includes a pressure sensorconfigured to measure pressure of the liquid in the liquid containerwhen the liquid container is coupled to the base unit.
 14. The system ofclaim 13, wherein the pressure sensor is configured to measure pressureagainst the flexible film.
 15. The system of claim 11, wherein thesecond tube has an inner diameter of more than about 5 mm.
 16. Thesystem of claim 1, wherein the membrane is non-porous.
 17. The system ofclaim 1, wherein the nasal cannula includes an outlet having a crosssectional area less than a cross sectional area of a patient's nostril.18. The system of claim 1, wherein the base unit further comprises anoxygen sensor.
 19. The system of claim 1, further comprising an oxygensource.
 20. The system of claim 1, further comprising an oxygenconcentrator.
 21. The system of any of claim 19 or 20, wherein theoxygen source includes an oxygen outlet, wherein the blower includes ablower inlet, the oxygen outlet being coupled to the blower inlet. 22.The system of claim 21, wherein the oxygen outlet is coupled to theblower inlet by a needle valve.
 23. The system of claim 1, wherein theblower includes a blower outlet and wherein the liquid containerincludes a liquid inlet and a liquid outlet, and wherein the liquidinlet and the liquid outlet are each spaced from the blower outlet by atleast 10 cm.